Body weight management techniques that aim to reduce weight in order to prevent obesity have been in demand for some time. For example, Patent Literature 1 (JP 2010-181377A) and Patent Literature 2 (JP 2008-304421A) disclose devices that calculate target values based on intra-day body weight changes. In Patent Literature 3 (JP 2007-226775A), meanwhile, the deviation of an actual body weight from a target body weight is calculated on a daily basis. Finally, in Patent Literature 4 (JP 2010-237805A), a target weight loss amount is calculated using the formula (current body weight)−(target body weight).